In order to capitalize on the advantageous features of peroxygen bleaches, considerable industrial activity has centered around the search for means to increase their bleaching effectiveness at reduced temperatures, particularly at temperatures of about 60.degree. C. and lower. A variety of compositions have been disclosed in the art which employ a peroxygen bleaching compound in combination with one or more "activator" compounds which are said to promote or otherwise augment the bleaching power of the peroxygen compound, especially at lower temperatures.
U.S. Pat. No. 2,955,905, Davies, et al., issued Oct. 11, 1960, discloses bleaching compositions containing hydrogen peroxide or inorganic persalts and organic carboxylic esters having a titer in the peracid formation of not less than 0.1 N sodium thiosulphate. The esters, which include isopropenyl acetate and .DELTA.'-cyclohexenyl acetate, are said to deliver improved bleaching at temperatures in the range of 50.degree.-60.degree. C.
U.S. Pat. No. 3,816,324, Fine, et al., issued June 11, 1974, describes dry bleaching compositions containing hydrogen peroxide releasing compounds and bleach activators which include various N-acyl azoles. Examples 12 and 13 disclose sodium perborate combined with N-octanoyl imidazole and N-palmitoyl imidazole, respectively. The compositions are said to be useful at relatively low water temperatures.
U.S. Pat. No. 3,640,874, Gray, issued February 8, 1972, describes activated peroxide bleaches containing various N-benzoylimidazole compounds.
Belgian Pat. Nos. 858,048 and 858,049, both published February 24, 1978, describe certain alpha-acyloxy(N,N')-polyacyl malonamide compounds said to be effective activators for peroxygen bleaches at low temperatures.
U.S. Pat. 3,822,114, Montgomery, issued July 2, 1974, relates to the use of aldehydes or ketones to activate certain peroxygen bleaching compounds, but not including those which release hydrogen peroxide in aqueous solution.
U.S. Pat. No. 3,130,165, Brocklehurst, issued April 21, 1964, discloses activated bleaching compositions containing inorganic peroxygen compounds and esters of phenols or substituted phenols with an alpha-chlorinated lower aliphatic carboxylic acid, e.g., chloracetic acid or alpha-chloropropionic acid.
Effective Bleaching with Sodium Perborate, Gilbert, Detergent Age, June 1967, p. 18-20, July 1967, p. 30-33, August 1967, p. 26, 27 and 67, describes various activators for sodium perborate and problems inherent in activating oxygen bleaches.
U.S. Pat. No. 3,661,789, Corey, et al., issued May 9, 1972, describes activated peroxygen bleaching systems which are stabilized using nonionic surfactants or glycols.
British Pat. 1,382,594, published February 5, 1975, discloses quaternary ammonium phenyl ester compounds as activators for hydrogen peroxide or per-salt bleaches. The activator is said to have both a per-acid generating structure and a fabric substantive structure. The fabric substantive structure of the activator is said to localize the bleaching species at fabric surfaces and thereby increase bleaching efficiency.
While the above compositions provide varying degrees of peroxygen bleach activation, there is a continuing need for more effective peroxygen activators as cool water bleaching and laundering practices become more common.
It has now been discovered that common peroxygen bleaching compounds can be activated by certain long chain acyl compounds to provide superior bleaching compositions which are stable, safe and highly effective at relatively low temperatures.